History of the Technology
In certain industrial applications, heavy, stiff, bulky metal wire rope slings have been replaced by lighter, flexible, synthetic fiber slings. Roundslings and flat slings are preferred by professional riggers when the particular application permits their use. Conscientious riggers are constantly seeking improved sling constructions so that they can safely govern the movement of their payload by controlling the direction of the vector forces acting on the loads which they are lifting, lowering and pulling. Flat sling constructions in which the individual component members, such as the sling and fittings, lie on the same plane are preferred over irregular, multi-dimensional sling constructions which contain bulky, unmanageable coupling members, such as shackles, turnbuckles and the like, which interfere with a connection of the coupling link, the sling, and the load in the same plane. There has been a need in sling technology for a coupling link which is a single fitting that can be adapted for any uses in connecting different load bearing pieces together in the same relative plane.
The prior art fittings were designed to accommodate wire rope or chain, but not synthetic slings, e.g. web, roundsling, and TWIN-PATH.RTM. slings. The flat sling must not be bunched or crimped by the fitting because it loses strength when this happens. It is preferred to present a flat sling with a flat fitting coupler link that is wide enough to support the sling at the sling's greatest width. The prior art fittings did not provide adequate sling bearing surface, they caused the synthetic slings to lose strength where the eye of the payload lifting device was joined to the coupling link. The large, unwieldy prior art fittings also increased the cost of assembly and disassembly of the sling construction.